Rotary-hearth furnace



Dec. 18, 1928. 1,695,883

,0. A. COLBY ROTARY HEARTH FURNACE Filed July 14, 1927 INVENTOR Ora A. 60/17) ATTO'RNEY Patented Dec. 18, 1928.

UNITED STATES 01m A. COLBY, or MANSFIELD, OHIO,

ASSIGNOR T WE STINGHOUSE ELECTRIC 8n MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

ROTARY-Emma FURNACE.

Application filed m 14,

My invention relates to furnaces and more particularly to furnaces of the rotaryhearth type.

In furnaces of the above-mentioned type,

employing tiltable hearth trays for carrying the material to be heated, the tray is usually constructed with an open end to facilitate the discharge of material therefrom when the tray is tilted. With such a r construction, difliculty has been experienced in maintaining the material upon the trays during the movement thereof through the furnace chamber.

. It is an object of my invention, therefore,

' to provide means for maintaining material to be heated .upon the trays of a rotaryhearth furnace during the movement thereof through the furnace chamber.

In practicing my invention, I provide, in

conjunction with a furnace structure and a hearth 'rotatably mounted therein, a plurality of material-carrying trays plvotally mounted on said hearth'and adapted to be tilted to effect the discharge of material carried thereby. In order to maintain the material upon said trays during the movement thereof through the furnace, I PIOVIdG a single annular strip which cooperates with all of said trays adjacent to the open ends thereof. As the trays are successively tilted, the annular strip is supported by the untilted trays, and the discharge end of the tray being tilted moves out of cooperative engagement therewith, thereby permitting the discharge of the heated material therefrom.

In the drawing, Figure 1 is a vertical section through a rotary-hearth furnace embodying my invention, and

Fig. 2 is a detail view of a hearth tray, the greater portion of the furnace structure being broken away.

Referring more particularly to Fig. 1, the furnace structure comprises a plurality of refractory heat-insulating walls 2 and a roo 4 enclosing an annular open-bottom furnace chamber 6. A metallic shell 8 encloses r the refractory structure and is supported upon suitable structural irons 10 and a vertical standard 12 coaxial with the annular furnace chamber.

A discharge chute 13 extends through the outer furnace wall into communication with the furnace chamber, to receive the heated 1927.' Serial N0. 205,552.

material, as hereinafter described. A suitable opening (not shown) is also provided to permit the charging of material into the chamber.

Heating of the furnace chamber is effected, in the present embodiment, by a sinuous metallic electrical resistor ribbon 14 supported upon the side walls thereof and electrically connected to a suitable source of electrical energy (not shown).

A rotatable hearth, comprising an annular hearth portion 15 of suitable refractory material substantially filling the open bottom of the furnace chamber, is supported upon a substantially circular plate'16 co-a-xial with the standard 12. Suitable brackets 18 secured to the standard 12 are provided, at their outer extremities, with friction-reducing rollers 20 which cooperate with a downturn'ed flange 22 on plate 16 to rotatably support the latter. Extensions 24 are formed on plate 16 and are provided, at the inner ends thereof, with suitable friction-reducing means 26 cooperating with the peripheral face of the standard 12 to mainll-8.11;! the plate 16 in axial alignment therewit On both sides of the hearth portion 15 are upon hearth trays 36 pivotally secured, ad: 9 jacent to the outer ends thereof, to supporting carriages 38 mounted upon the hearth portion 15. The hearth trays 36 are formed with the outer ends thereof open, so that, upon the tilting thereof, material carf ried thereon may be discharged.

Successive tilting of the trays 36 is effected by means of a hook 40 depending through a suitably hushed opening in the furnace -roof and ending in a portion 42 bent at right angles thereto. The bent portion 42 at the upper end of the hook 40 cooperates with a cam slot formed in the peripheral face of a rotatable drum 44 operatively connected to, and driven by, an electrio motor 46. The arrangement is such that a complete rotation of the drum 44 raises the hearth to discharging position and permits the return thereof to its normal untilted position.

Since the structure described thus far represents a common type of rotary-hearth furnace, with a usual tray-tilting means therefor, more detailed description thereof is not deemed necessary.

A portion ofthe side Walls of each of the trays 86 is recessed, as at 50, adjacent to the open end of the tray to receive the recessed. peripheral edge of an annular retaining strip 52. The strip 52 isformed of suitable refractory material and is adapted to be supported by the recessed portions of the hearth trays and to substantially close the open ends thereof.

In operation, if it is desired to discharge the. contents of a hearth tray when the same is in alignment with the discharge chute 13, the rotation of the hearth is stopped and the tray-tilting motor 46 is energized. During the tilting of the tray, the retaining strip 52 is supported by the non-tilted trays, so that the discharge end of the tray being tilted is lowered out of engagement with the retaining strip, thereby permitting the discharge ofthe material into the discharge chute 13.

\Vhile I have shown and described a particular embodiment of my invention, quite obviously, I may depart considerably therefrom within the scope thereof. For example, changes may be made in the design and construction of the hearth-supporting means, of the tray-tilting means and the particular design of the tray and retaining strip, and

still be within the scope 'of the present invention.

By my invention, I have provided an improved means for maintaining material being heated upon the tiltabletrays of a 1'0- tary-hearth furnace, which is effective. in operation and highly practicable from a structural standpoint. v

Modifications may. be made in my inven tion without departing from the spirit and scope thereof, and I desire, therefore, that only such limitations shall be placed thereon as are imposed by the prior art and set forth. in the appended claims.

I claim as my invention:

1. In a rotary-hearth furnace, the combination with a rotary-hearth and a plurality of material-carrying trays pivotally mountthereon, and means for tilting said trayssuccessively to effect the discharging thereof, of a means cooperating with the open ends of all of said trays to normally close the same, said closing means being disengaged from said trays successively as each one is tilted.

8. In a furnace, the combination with a plurality of pivotally mounted trays adapted to be moved through said furnace, and means for successively tilting said trays, of a means supportedby said trays for normally maintaining material thereon, whereby,

upon tilting of each tray, said means is supported by the untilt ed trays, thereby permitting the discharge of material from said tilted tray.

4. In a furnace, the combination with an annular hearth and a plurality of open-end material-carrying trays pivotally mounted thereon, of an annular ring co-axial with, said hearth, means adjacent to the open ends" of said trays for receiving a. peripheral portion of said ring in supporting relation to close'the open ends thereof, and means for successively tilting said trays, thereby moving the ends thereof out of engagement with said ring to permit the discharge of material ,therefrom.

5. In a furnace, the combination of a plurality of open-ended hearth trays mounted for movement through said furnace, and

means for successively tilting said tra s to effect the discharge of; material there rom, of lneans for normally closing the openends of said trays comprising a strip of suflicient length to engage, and be supported upon, the lateral edges of a plurality of said trays and recessed to permit the closure of the open ends of said trays thereby.

In testimony whereof, I have hereunto subscribed my name this 22 day of June,

1927. ORA A. coLBY. 

